86 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 



by numbers 1 to 5 ; the main sheet is shaded, and the anterior and pos- 

 terior are located on either side of it ; the faults are drawn as broken 

 lines. Finally, a section drawn at right angles to the prevalent trend 

 of the faults is given in Fig. 17; it is not constructed closely to scale, 

 but indicates the general structure of the region. The abnormal Short 

 Mountain fault, with downthrow on the southeast, which when first 

 found seemed to endanger our generalization, is seen to be only a single 

 exception to a well marked rule. No other explanation of the structure 

 of the region than that by faulting seems admissible. 



It has been difficult and in most cases as yet impossible to trace the 

 faults far to either side of the three trap ridges ; elsewhere, the surface 

 is so heavily drift-covered, and the sandstone or shale ridges are so 

 monotonous, that dislocations cannot be demonstrated. But it is in the 

 highest degree probable that the faults are not limited to the belt 

 of trap ridges ; the uniformity of direction and of throw over the con- 

 siderable district where we have traced them indicate their extension 

 over a much larger area, where more patient search may yet detect 

 them. 



The Triassic monocline must therefore be regarded as composed, in 

 the Meriden-New Britain district, of a number of long and relatively 

 narrow blocks, whose direction is oblique to the strike of their beds, but 

 is in a most striking way accordant with the trend of the fundamental 

 schists, where they are exposed to the southwest and northeast, I find 

 it impossible to resist the conviction that this accordance is not due to 

 chance, but that it points to physical dependence of the superficial on 

 the deeper structure, as has been suggested in my earlier papers. 



Cambridge, Mass., March 27, 1889. 



